There are several people here who should be involved, and there are two people to consider whose lives are being impacted in an unhealthy manner. I think there needs to be some adult intervention here.
The girl's parents absolutely need to be informed
Whatever the true intent behind the girl's suicidal expressions, they are still suicidal expressions. The girl's parents need to be informed.
Turn this around: if your son were telling someone he was suicidal, and his friend's parents were trying to "deal with this insofar as it impacted their daughter" without telling you, and your son then disappeared/committed suicide, how would you feel that they didn't tell you about it?
The girl's parents need to find her a therapist
This is absolutely not your job. It's not your daughter. If, and only if, the parents seem to be paying absolutely no attention to her issues (you do have some degree of right to this information), then it should be brought up with the girl's school counselor.
Your son is not a trained therapist, and no one has the right to ask him to take on this burden
She may want him to help her by listening, but this is beyond the ability of a 15 year old to handle wisely.
"He is really sweating over trying to fix her."
That's because he hasn't had a formal education and a few years worth of supervised clinical training in how to handle this. Of course he's in a bad bind. She has given him a responsibility he is not prepared for, and should never have been given.
Did he come to you and tell her of his girlfriend's problems? Did he seek your advice on how to handle it? This would have been a wise thing to do. If he didn't, and you only found out because he wanted badly to continue talking when he was supposed to be doing something else, you can use this fact when you talk to him about why he's ill-equipped to handle the girl's problems.
At her age, school should come first; at his age, relationships should not get your son in trouble in school.
This girl is only 13 and so doesn't have any exams herself.
You and I understand exams differently. Certainly she goes to school? Somehow she gets grades? Are tests different than exams?
It really doesn't matter. This 13 year old girl is not making your son and his well being a high priority. She's only 13, and can't do that yet. She's a bit young to be in such a time-consuming relationship with a boy. If he wants to take care of her (or anyone else) someday, he needs to be in a position to do so. If he isn't a natural wizard at some marketable skill, he needs to learn one. She shouldn't be interfering with his ability to do so.
You are his parents, and his well-being needs to come first to you. You have an obligation to inform the girl's parents, and maybe school counselor - which you should fulfill ASAP - about her condition, then start setting limits on this relationship. That is your responsibility to your son and his future.
While he may well balk, that's no reason not to step in as parents. I see two possible benefits to putting limits on the time they may spend (in person or on any device) together:
- Your son will have more free time to pursue healthier ways to spend his time, and
- she may stop seeing him as a comfort-object, either encouraging her to use more appropriate channels to deal with her issues, or to move on to someone who has more free time to spend on her.
He doesn't see any of his friends any more. They came up with an arrangement that they were only to spend time with each other.
In an adult relationship, this would be seen as a precursor to potential abuse. Social isolation means that the isolator is in the position to meet all the the isolated's emotional needs. Or not to. It's a means of control. Explain to your son that this is an unreasonable and unhealthy request for someone to make of him. Hanging out with groups of friends with occasional time alone together is a more normal and healthy relationship for their ages.
When we get in the way and take his phone away because of homework and such he gets really stressed telling us that this girl is in real trouble and needs his help.
That's what her parents, her counselor(s), Child Protection Services, the police, and suicide hotlines are for.
I come to take his phone away at bed time and the kid completely freaks out. He bangs on about how he misses her and he just wants more time with her and he needs the phone just to hear her say I love you one more time.
At his age, this is important to him: to have a female love interest, to be loved, to feel he's in an adult(ish) relationship independent of you, etc. But it's also an immature, unhealthy relationship, and he needs to understand that you are looking out for him out of love and concern. If he absolutely refuses to believe you, make an appointment with his school counselor, discuss the situation, then meet with them with your son. The counselor should shed some light on your son's you-don't-understand-you're-my-parents type objections. If therapy is free in your country, or covered by insurance, he might benefit from examining his own need to be a such an important figure in a relationship with someone else. Wanting to be loved is normal. Wanting to provide full-time therapy is not.
I answer and tell her son needs his sleep. He spends the next hour crying loudly and banging his wall.
It has to end sometime. Grit your teeth, and try not to let him keep the neighbors up.
Take control of his electronics, and make sure he's using them for schoolwork, talking to other friends, etc., as well as some reasonable amount of time - limited - with his young friend.
Use all your parenting skills (or read about parenting and setting limits with adolescents and teens) to help him sort out this mess he's in. Talk often, listen more, and learn about what your son needs. She is meeting a need in him. Try to supply some of what he needs and get him to explore different pathways to getting them met through other relationships. Recognition of and positive reinforcement for good decisions is important always. Negotiate. Teach him about healthy boundaries, so he can learn to set them.
No one with normal teenagers says parenting is a breeze. Still, you have to make the effort. He won't like it, but it' your job.